Answer:

Explanation:
To convert atoms to moles, Avogadro's Number must be used: 6.022*10²³.
This tells us the amount of particles (atoms, molecules, etc.) in 1 mole of a substance. In this case it is the atoms of potassium. We can create a ratio.

Multiply by the given number of moles: 15.2

The moles of potassium cancel.

The denominator of 1 can be ignored.

Multiply.

The original measurement of moles has 3 significant figures, so our answer must have the same. For the number we calculated that is the hundredth place. The 3 in the thousandth place tells us to leave 5.

In 15.2 moles of potassium, there are <u>9.15*10²⁴ atoms of potassium.</u>
Answer:
74.0 g/mol
Explanation:
Step 1: Write the generic neutralization reaction
HA + NaOH ⇒ NaA + H₂O
Step 2: Calculate the reacting moles of NaOH
At the equivalence point, 33.83 mL of 0.115 M NaOH react.
0.03383 L × 0.115 mol/L = 3.89 × 10⁻³ mol
Step 3: Calculate the moles of HA that completely react with 3.89 × 10⁻³ moles of NaOH
The molar ratio of HA to NaOH is 1:1. The reacting moles of HA is 1/1 × 3.89 × 10⁻³ mol = 3.89 × 10⁻³ mol.
Step 4: Calculate the molar mass of the acid
3.89 × 10⁻³ moles of HA have a mass of 0.288 g.
M = 0.288 g / 3.89 × 10⁻³ mol = 74.0 g/mol
The number of neon moles that occupy a volume of 14.3 l at STP is calculated as follows
At STP 1 mole = 22.4 liters
what about 14.3 liters
by cross multiplication
= (1 mole x 14.3 l)/22.4 l =0.638 moles of neon